*CLI> module show like CALLER
Module                         Description                              Use Count
func_callerid.so               Caller ID related dialplan function      0
1 modules loaded
*CLI> module unload func_callerid.so
  == Unregistered custom function CALLERID
*CLI> module show like CALLER
Module                         Description                              Use Count
func_callerid.so               Caller ID related dialplan function      0
1 modules loaded

[So the module is still present.]

*CLI> module unload func_callerid.so
Unable to unload resource func_callerid.so
*CLI>